# if判断
# age = 21
# if age < 20:
#     print("<20")

# a = 11
# b = 15
# if a > 10 and b < 20:
#     print("区间内")
# else:
#     print("区间外")

# 三目运算
# a = 3
# b = 2
# print("a <= b") if a <= b else print("a > b")

# if-elif
# number = 61
# if 80 <= number <= 100:
#     print("优秀")
# elif 60 <= number < 80:
#     print("良好")
# elif 0 <= number < 60:
#     print("不及格")
# else:
#     print("无效分数")

# if嵌套
# flag1 = input();
# flag2 = input();
# if flag1 == "no tickit" :
#     if flag2 == "follow":
#         print("out the train")
#     elif flag2 == "dont follow":
#         print("in the prison")
# else:
#     print("have a nice trip")
#
